Continuous Process Improvement (CPI) is an OSD initiative focused on "continuous process improvement to maximize weapon system readiness while minimizing materiel flows and in-process inventories." The goal is to optimize reliability and cycle time while striking a reasonable balance with costs across the total life cycle value chain, employing:

Lean — for eliminating all types of waste

Six Sigma — for optimizing process variation

Theory of Constraints — for alleviating process bottlenecks

MIT defines lean as "elimination of waste and efficient creation of enterprise value" and includes "optimization of value delivered to all stakeholders and enterprises in value chain." According to the Lean Aerospace Initiative, "lean thinking is a dynamic, knowledge-driven, customer-focused process by which all individuals within an enterprise — indeed, the enterprise itself — continuously eliminate waste and expense, maximize resources and streamline operations, and create a total enterprise transformation endowed with added value. Lean tools and practices have been consistently shown to help target, identify, define, and implement improvements across a broad spectrum of enterprises."